Our voice phone systems are seamlessly federated. You can call people across carriers, over national boundaries, instantaneously, and the only friction is slightly more numbers to dial.
SMS is also remarkably well federated. In the early 2000s, every carrier had their own text messaging platform. Today, you can send an SMS to practically anyone.
So here's my question: why the hell do we mess around with so many proprietary OTT services? Why do you have some friends who WhatsApp, others who Telegram, others who Signal? Why do we have to figure out whether to Zoom or Meet or FaceTime or Jitsi? We are literally all carrying phones 24x7. Let's just use our phones.
@evan SMS is well-federated, but also the very lowest common denominator. It excels at nothing else.
The designers of systems are making choices, often based on how much access they want to your data.
I'm happy to use Signal, because they don't want my data.